BLOOD PRESSURE
Blood pressure is the pressure blood exerts against the walls of the vessels in which it is contained.
Blood pressure may be defined as the force exerted by blood against the walls of the vessels in which it is contained. Differences in blood pressure between different areas of the circulation provide the driving force that keeps the blood moving through the body
Purpose
- To obtain baseline date for diagnosis and treatment
- To compare with subsequent changes that may occur during care of patient
- To assist in evaluating status of patients blood volume. Cardiac output and vascular system
- To evaluate patients response to change in physical condition as a result of treatment with fluids or medications
Indications
- To determine baseline, blood pressure recording and monitor fluctuation
- To aid in the diagnostic disease
- To aid in the assessment of cardiovascular system
Type of pressure
- Systolic pressure: it is the highest degree of pressure exerted by the blood against the arterial wall as the left ventricle contracts and forces the blood from it into the aorta
- Diastolic pressure: it is the lowest degree if pressure when the pressure is in its resting period just before contraction of the left ventricle
- Pulse pressure: it is the difference between systolic and diastolic pressure for the health, adult is usually about 120/180 (systolic pressure 12 mm Hg and diastolic pressure 80 mm Hg with pulse pressure of 40 mm Hg)
- Normal venous pressure on an average person in a recumbent position is 40 to 110 mm of water. Venous pressure is a valuable index in determining the efficiency of heart muscles
Scientific Principles
- Exercise, emotion, anxiety, fear, tension and worry cause a temporary rise in blood pressure
- The brachial artery in the antecubital area which is convenient place for taking BP
- A noisy environment and parallex error interfere with correct reading on manometer
- A twisted cuff may produce unequal pressure and can cause inaccurate reading
- Accurate reading is possible only when the stethoscope is directly over the artery
- Airtight system of cuff and tubing facilitates accurate reading
- Sufficient pressure in the cuff obliterates the flow of blood through the brachial artery
Factors Influencing Blood Pressure
- Age: adult’s blood pressure tends to increase with advancing age. The older adult’s blood pressure is 140-160/80-90 mm Hg
- Stress: anxiety, fear and pain and emotional stress increase blood pressure
- Medication: narcotic and analgesics lower blood pressure
- Diurnal variation: it is lowest in early morning and higher in later evening
- Sex: in men, it is higher than in female
- Exercise: it will increase blood pressure
- Bleeding: it causes low blood pressure
Blood pressure – (systolic) – (Diastolic)
Newborn – 30-50 mm hg – 10 mm Hg
Infant – 70-90 mm Hg – 50 mm Hg
Preliminary Assessment
- Identify the patient
- Check the diagnosis, reason for taking BP schedule frequency of obtaining blood pressure
- Previous measurement and range of blood pressure
- Physical and mental state of the patient. Avoid blood pressure taking, on a patient who is angry, anxious or in pain or a crying child
- Assess the arm on which the blood pressure can be taken. Do not take blood pressure reading on a patient’s arm if:
The arm has an intravenous infusion on it
The arm is injured or diseased
The arm has a shunt or fistula for the renal dialysis
On the same side of the body where a female patient had a radical mastectomy
Preparation of the Article
- Sphygmomanometer
- Stethoscope
- Piece of paper
Preparation of the Article
- Explain the procedure to the patient to gain the confidence and cooperation of the patient
- Place the patient in a comfortable position either lying down with the arm resting on the bed or sitting with the arm supported on the table at heart level to ensure accurate reading
- Patient should be resting at least 5 to 10 minutes prior to taking blood pressure
Guidelines
- The sphygmomanometers generally used in clinical setting are mercury type and aneroid type. The mercury type sphygmomanometer is more reliable than the aneroid type sphygmomanometers. The aneroid sphygmomanometers give blood pressure reading on dial indicator
- Systolic pressure is increased in pressure induced by systolic contraction and diastolic pressure is decrease in pressure induced by diastolic relaxation of the left ventricle of heart
- Never take blood pressure when the patient is excited, exhausted and just after exercise, smoking or meals
- Allow the patient to rest for five minutes before taking blood pressure
- Do not use the extremity that is injured, diseased, paralyzed, receiving intravenous infusion or when a female patient is with radical mastectomy on the same side
- When the arm cannot be used to measure the blood pressure, the thigh can be used being a good alternative site
- Always take the blood pressure reading on the same side and in the same position to maintain consistency
- Place the site (arm or leg) about the level of heart while taking blood pressure
- The apparatus should be in working order. The cuff should be of appropriate size (12-14 cm for arm and 18-20 cm for thigh) and deflated before wrapping around the patient’s site
- While taking blood pressure, certain sounds are heard in sequence. These are called as Korotkoff sounds and are described as under:
Tapping: the faint clear sounds that gradually become louder, the first tapping sound may be followed by an absence of sound (auscultatory gap) and indicates systolic pressure reading
Murmuring: the low swishing sounds that increase with cuff deflation
Knocking: the crisp, clear sounds that occur with each heart beat
Muffling: abrupt change of sound indicates first diastolic pressure reading
No sounds: the sound disappears and indicates second diastolic pressure reading
- When deflating the cuff to take the readings, deflate the cuff to 0. Do not stop in between and start inflating again as this gives a false reading
- Note the variations in blood pressure
Procedure
- Wash hands
- Take the equipment to the bedside
- Apply deflated cuff evenly with rubber bladder over the brachial artery, the lower edge being “2” inch above the antecubital fossa. The two tubes turning towards the palm
- Palpate the brachial artery with the finger tips. Place the bell of the stethoscope on the brachial pulse. The stethoscope must hang freely from the ears
- Close the valve on the pump by turning the knob clockwise. Pump up air in the cuff until the sphygmomanometer registers about 20 mm above the point at which the radial pulsation disappears
- Open the valve slowly by turning the knob anti-clockwise. Permit the air to escape very slowly. Note the number on the manometer where sound first begins. This is the systolic pressure
- Continue to release the pressure slowly. The sound become louder and clearer. Note the point on the manometer where the sound ceases. This is the diastolic pressure
- Allow the air to escape and the mercury to fall zero. Wait for one minute with the cuff deflated
- Repeat the procedure if there is any doubts about the reading
- Do not take blood pressure more than three times in succession on reading the same arm
After Care
- Remove the cuff by rolling it and replace it in the box
- Assist the patient to cover the arm which was exposed
- Take the apparatus to the duty room and keep it safely in the cupboard
- Wash hands and record the readings immediately, with the date and time
Variations in Blood Pressure
Hypertension
Elevated or high blood pressure is known as hypertension. Hypertension is a major factor causing deaths from strokes and myocardial infarction (heart arrest)
Causes of Hypertension
- Family history of hypertension
- Obesity
- Cigarette smoking
- Alcohol consumption
- High blood cholesterol level
- Continued exposure to stress
- Old age
Treatment
- Early diagnosis
- Long-term follow up care and therapy
Hypotension
When the systolic pressure falls to 90 mm Hg or below, that condition is known as hypotension
Causes of Hypotension
- Dilatation of the arteries
- Loss of blood, due to hemorrhage
- Failure of heart muscle to pump adequately (heart attack)
Sign and Symptoms of Hypotension
- Pallor
- Skin mottling
- Cold and clammy skin
- Increased heart rate
- Decreased urine output
